142 



NATURE 



[June io, 1897 



There can be no doubt that some of the polytechnic institu- 

 tions in London are moving towards a higher educational status 

 than they occupied a few years ago. The courses of study are 

 systematised, and they are supervised by teachers who have 

 had laboratory experience ; hence they educate the mind as well 

 as train the hand. An announcement that, in the next session 

 (1897-98) Principal Tomlinson, F.R.S., of the South-west 

 London Polytechnic, will establish a class for training in research, 

 affords an instance of the higher tendency of polytechnic in- 

 struction. This research training will form part of the curriculum 

 of the second year day electrical engineering students of the 

 institute, but will be open to a limited number of other students 

 provided they can show a fair knowledge of the elementary 

 principles of physics and mathematics. The method of con- 

 ducting any research will be as follows : — The Principal will 

 first select some subject for investigation suitable for electrical 

 engineering students. He will then fully explain to the class 

 the various reasons which have induced him to make the 

 selection, and will give a brief history of what has been pre- 

 viously done round and about the subject, and full reference 

 thereto. He will also propound a mode or modes of attacking 

 the research, and invite criticisms from the class. When the best 

 mode of attack has been decided on, the class will be expected 

 not only to take part in the experiments, but to help in preparing 

 the required apparatus. Should the results obtained be of suffi- 

 cient importance, they will be offered in the form of a paper to 

 such societies as the Royal Society, the Physical Society, or the 

 Institution of Electrical Engineers. From time to time during 

 the investigations the Principal will give demonstrations or 

 lectures on those particular branches of magnetism and electricity 

 which bear directly on the investigation, and will illustrate them 

 by the results obtained. The subject selected for the first 

 research is "the effect of repeated heating on the magnetic 

 permeability and electrical conductivity of iron and steel." 



SOCIETIES AND ACADEMIES. 

 London. 



Royal Society, May 13. — "On the Passage of Heat 

 between Metal Surfaces and Liquids in contact with them." 

 By T. E. Stanton, M.Sc. Received April 7. 



An experimental investigation was undertaken to determine 

 the rate of transmission of heat from the walls of a heated metal 

 pipe to colder water flowing through it. By means of the appa- 

 ratus constructed for this purpose the velocity, initial and final 

 temperatures, and pressure of the water, also the surface tem- 

 perature of the pipe, could be observed ; and by varying the 

 initial temperature and velocity of the water, the effect of vary- 

 ing ranges of temperature and velocity of water could be 

 experimentally studied. 



The results of the experiments showed that the heat trans- 

 mitted from any small surface of the pipe 



( 1 ) was independent of the pressure of the water ; 



(2) was proportional to the range of temperature between the 



surface and the flowing water ; 



(3) was approximately proportional to the velocity of the 



water ; 



(4) was proportional to a function of the viscosity of the 



water ; or, putting 

 H = heat transmitted, S = surface of pipe, 



V = velocity of water, T„ — surface temperature of 



pipe, 

 t = temperature of water, 



that ^g-= k. (T„ - t) V"' (I -f aTJ (i -)- jS/) 



where m = "85 o = -004 fi = -oi. 



It is also shown that these results are in accordance with 

 Prof. Osborne Reynolds' theory of the convection of heat from 

 a hot surface to water flowing over it, this theory being that the 

 motion of heat in the pipe follows the same law as the motion 

 of momentum, as far as convection and conduction are con- 

 cerned ; so that, from Prof. Reynolds' equation for the fall of 

 pressure in a pipe, the value of the slope of temperature may be 

 expressed, the constants in which may be determined by experi- 

 ment. 



In this theoretical expression for the slope of temperature it 

 is seen that the effect of the velocity of the water is very small, 

 which is the most remarkable fact brought out by the experi- 

 mental research. 



" On the Magnetisation Limit of Iron." By Henry Wilde, 

 F.R.S. Received April 3. 



In a former paper read before the Society, " On the Influence 

 of Temperature on the Magnetisation of Iron," the author 

 described a new method of determining the magnetisation limit 

 of magnetic substances, by which, with a single pole of an 

 electro-magnet, a more exalted degree of magnetisation was 

 indicated, as measured by the force of traction, than had pre- 

 viously been attained {Roy, Sac. Proc, 1891, vol. 1.). The 

 magnetisation limit of iron, as deduced from his experiments, 

 was 381 pounds per square inch of section, and it appeared to 

 him at the time that the extreme limit was well within 400 

 pounds per square inch. The author has recently had occasion 

 to repeat these experiments with other specimens of iron 

 of different lengths, and has increased the magnetisation 

 limit to 422 pounds per square inch, or 29*67 kilos, per square 

 centimetre. He describes an experiment showing that the single- 

 pole method of determining the magnetisation limit of magnetic 

 substances compares favourably with the double-pole method, 

 and that no higher degree of tractive force is to be expected from 

 the latter than has been obtained from the former method. 



Linnean Society, May 6.— Dr. A. Gunther, F.R.S., 

 President, in the chair. — Prof Ludwig Radlkofer, of Munich, 

 was elected a Foreign Member. — Prof. Stewart, F.R.S., 

 exhibited and made remarks on some anatomical prepara- 

 tions showing the different modes of attachment of the Lig- 

 amentum nucha in herbivorous and carnivorous mammals, as 

 exemplified in the sheep and dog, and of the Ligamenta subjlava. 

 The analogous ligaments of birds were dealt with, and special 

 attention was drawn to a preparation of the vertebral column of 

 the python, showing vertebra-costal fibro-cartilaginous plates of 

 which he could find no description and which he believed to be 

 peculiar to the Ophidia. — The Secretary read the abstract of a 

 paper by Messrs. W. and G. S. West, on Desmids from Singa- 

 pore. These had been discovered in a small collection of Algse 

 forwarded by Mr. H. N. Ridley from Singapore, and, in addi- 

 tion to seven species previously known from Sumatra, contained 

 several which were new, and now described and figured. — Prof 

 Newton, F.R.S., communicated a paper by Captain F. W. 

 Hutton, Curator of the Canterbury Museum, Christchurch, 

 N.Z., entitled " The Problem of Utility," in which the views of 

 Dr. A. R.Wallace on "The Utility of Specific Characters " 

 {Journ. Linn. Soc. Zool., xxv. pp. 481-496) were criticised, 

 chiefly as tested by the study of the fruit-pigeons {Ptilopus). — 

 The Secretary gave an account of a paper by the Rev. R. Bogg 

 Watson, on some new species of Mollusca from the Island of 

 Madeira, prefacing his remarks with a brief rdsutne of the 

 researches previously made in the same direction by Messrs. 

 Lowe, WoUaston, and other conchologists. 



Chemical Society, May 20. — Prof, Dewar, President, in 

 the chair. — The following papers were read : — The theory of 

 osmotic pressure and the hypothesis of electrolytic dissociation, 

 by H. Crompton. It is shown that van 't Hoffs view — that the 

 osmotic pressure of a dissolved substance in dilute solution is 

 equal to the pressure which the substance would exercise in the 

 same volume if gaseous — holds when the dissolved substance 

 and the solvent form normal or monomolecular liquids, and may 

 hold when both liquids are associated, but does not hold when 

 one only of the two liquids is associated. When either solvent 

 or dissolved substance is associated, van 't Hoff's formula for the 

 molecular reduction of the freezing point requires modification ; 

 on working with the modified formula, it is found that the 

 results obtained accord with the view that electrolytes are 

 monomolecular compounds dissolved in an associated solvent, 

 namely water. The hypothesis of electrolytic dissociation is 

 thus unnecessary for explaining cases of this kind, and is further 

 inconsistent with what is known of the molecular character of 

 liquids. The cube of the association factor of a liquid is 

 approximately proportional to its specific inductive capacity. — 

 Molecular rotations of optically active salts, by H. Crompton. 

 The fact that optically active salts of strong acids have the same 

 equivalent rotations in dilute solution is generally quoted in 

 support of the dissociation hypothesis ; the author shows, how- 

 ever, that similar regularities are observed in the case of other 

 salts which are certainly not electrolytically dissociated, so that 

 it would seem that monomolecular salts containing a common 

 optically active radicle have the same equivalent rotation. — 

 Heats of neutralisation of acids and bases in dilute aqueous 

 solution, by H. Crompton. The author explains the constancy 



NO, 1 44 1, VOL. 56] 



